Rename base loop() to try_drain_overflow_buffer_() inline helper

The base class loop() only drained the overflow buffer. Rename to
make intent clear and inline it so the compiler can optimize across
the call boundary. Make loop() pure virtual since subclasses always
override it.

esphome/components/api/api_frame_helper.cpp

@@ -100,17 +100,6 @@ const LogString *api_error_to_logstr(APIError err) {
   return LOG_STR("UNKNOWN");
 }
 
-// Default implementation for loop - handles draining overflow buffer
-APIError APIFrameHelper::loop() {
-  if (!this->overflow_buf_.empty() && this->overflow_buf_.try_drain(this->socket_.get()) == -1) {
-    HELPER_LOG("Socket write failed with errno %d", errno);
-    if (this->check_socket_write_err_(errno) != APIError::WOULD_BLOCK)
-      return APIError::SOCKET_WRITE_FAILED;
-  }
-  // Convert WOULD_BLOCK to OK to avoid connection termination
-  return APIError::OK;
-}
-
 // This method writes data to socket or buffers it
 APIError APIFrameHelper::write_raw_(const struct iovec *iov, int iovcnt, uint16_t total_write_len) {
   // Returns APIError::OK if all data was sent or successfully queued.

esphome/components/api/api_frame_helper.h

@@ -105,7 +105,7 @@ class APIFrameHelper {
   }
   virtual ~APIFrameHelper() = default;
   virtual APIError init() = 0;
-  virtual APIError loop();
+  virtual APIError loop() = 0;
   virtual APIError read_packet(ReadPacketBuffer *buffer) = 0;
   bool can_write_without_blocking() { return this->state_ == State::DATA && this->overflow_buf_.empty(); }
   int getpeername(struct sockaddr *addr, socklen_t *addrlen) { return socket_->getpeername(addr, addrlen); }
@@ -190,6 +190,16 @@ class APIFrameHelper {
   }
 
  protected:
+  // Drain any backlogged overflow data to the socket.
+  // Returns OK even for WOULD_BLOCK to avoid connection termination.
+  APIError try_drain_overflow_buffer_() {
+    if (!this->overflow_buf_.empty() && this->overflow_buf_.try_drain(this->socket_.get()) == -1) {
+      if (this->check_socket_write_err_(errno) != APIError::WOULD_BLOCK)
+        return APIError::SOCKET_WRITE_FAILED;
+    }
+    return APIError::OK;
+  }
+
   // Common implementation for writing raw data to socket
   APIError write_raw_(const struct iovec *iov, int iovcnt, uint16_t total_write_len);
 

esphome/components/api/api_frame_helper_noise.cpp

@@ -153,8 +153,7 @@ APIError APINoiseFrameHelper::loop() {
     }
   }
 
-  // Use base class implementation for buffer sending
-  return APIFrameHelper::loop();
+  return this->try_drain_overflow_buffer_();
 }
 
 /** Read a packet into the rx_buf_.

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -64,8 +64,7 @@ APIError APIPlaintextFrameHelper::loop() {
   if (state_ != State::DATA) {
     return APIError::BAD_STATE;
   }
-  // Use base class implementation for buffer sending
-  return APIFrameHelper::loop();
+  return this->try_drain_overflow_buffer_();
 }
 
 /** Read a packet into the rx_buf_.